If you are getting a CPO it has an extra warranty, which you an probably still add to. If you are buying a vehicle that is not certified the finance office will offer you extended service contract coverage. A used vehicle doesn't usually qualify for the same policy as a newly purchased vehicle, but there will be one available, and very likely Mazda has one. Coverage wise there won't be any large differences. Dealerships have different service contracts and often have relationships with third-party companies. Some dealers do not offer the Mazda contract first so if you want one you will need to ask. All this will be presented to you by the dealership finance manager.